[java-intentions] UnimplementInterfaceAction: do not try to remove synthetic methods

Fixes IDEA-354044 Error in Unimplement Interface when invoked on record

GitOrigin-RevId: 9c07e03d1f86ded0aeea3bd0f373dfc263e72eb4

java/java-impl/src/com/intellij/codeInspection/actions/UnimplementInterfaceAction.java

@@ -134,7 +134,7 @@ public class UnimplementInterfaceAction extends PsiUpdateModCommandAction<PsiEle
     for (PsiMethod psiMethod : psiMethods) {
       if (superMethods.contains(psiMethod)) continue;
       final PsiMethod impl = implementations.get(psiMethod);
-      if (impl != null) impl.delete();
+      if (impl != null && !(impl instanceof SyntheticElement)) impl.delete();
     }
   }
 

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/unimplement/afterRecord.java

@@ -0,0 +1,5 @@
+// "Unimplement" "true-preview"
+interface Iface {
+  int value();
+}
+record R(int value) {}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/unimplement/beforeRecord.java

@@ -0,0 +1,5 @@
+// "Unimplement" "true-preview"
+interface Iface {
+  int value();
+}
+record R(int value) implements Ifa<caret>ce {}